iPadOS:防止UIContextMenuInteraction在不使用指针时触发

Question

UIMenu对UIContextMenuInteraction对UIPointerInteraction

我试图以与文件或页面应用程序相同的方式设置UIContextMenuInteraction：

• (Long)点击空格中的任意位置显示黑色水平的

(右/控制)单击空格中任何位置的指针，显示上下文菜单

参见下面附加的GIF演示。

我能够设置UIContextMenuInteraction，并在它的UIContextMenuInteractionDelegate中用我想要显示的项返回UIContextMenuConfiguration。

同样，对于小型黑色UIMenu，我可以使用UILongPressGestureRecognizer并使用UIMenuController.shared.showMenu显示菜单。

但是，我无法阻止UIContextMenuInteraction在视图上长时间按下时触发和显示UITargetedPreview，而且现在似乎有办法通过提供给UIContextMenuInteractionDelegate的信息来识别不同的UITouchType。

在没有UIContextMenuInteraction的情况下，我也找不到如何以编程方式显示上下文菜单。有办法吗？

问题

这是如何在Files.app中实现的？

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Answer 1

没有办法以编程方式触发上下文菜单，但是通过一些简单的簿记，您可以防止它在不需要的时候显示出来(例如，当触点在响应程序上处于活动状态时)。

若要隐藏预览，只需在UIContextMenuConfiguration的初始化程序中从previewProvider中返回零。

下面是一个以视图控制器的视图为目标的完整实现：

import UIKit

class ViewController: UIViewController {

    var touchesInSession = false

    override func viewDidLoad() {
        super.viewDidLoad()

        let interaction = UIContextMenuInteraction(delegate: self)
        view.addInteraction(interaction)

        let recognizer = UILongPressGestureRecognizer(target: self, action: #selector(longPressHandler))
        view.addGestureRecognizer(recognizer)
    }

    @objc func longPressHandler(recognizer: UILongPressGestureRecognizer) {
        guard recognizer.state == .began else { return }
        presentMenu(from: recognizer.location(in: view))
    }

    func presentMenu(from location: CGPoint) {
        view.becomeFirstResponder()
        let saveMenuItem = UIMenuItem(title: "New Folder", action: #selector(createFolder))
        let deleteMenuItem = UIMenuItem(title: "Get Info", action: #selector(getInfo))
        UIMenuController.shared.menuItems = [saveMenuItem, deleteMenuItem]
        UIMenuController.shared.showMenu(from: view, rect: .init(origin: location, size: .zero))
    }

    @objc func createFolder() {
        print("createFolder")
    }

    @objc func getInfo() {
        print("getInfo")
    }

    // MARK: UIResponder
    override var canBecomeFirstResponder: Bool { true }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesBegan(touches, with: event)
        touchesInSession = true
    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesEnded(touches, with: event)
        touchesInSession = false
    }

    override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesCancelled(touches, with: event)
        touchesInSession = false
    }
}

extension ViewController: UIContextMenuInteractionDelegate {
    func contextMenuInteraction(_ interaction: UIContextMenuInteraction, configurationForMenuAtLocation location: CGPoint) -> UIContextMenuConfiguration? {
        guard !touchesInSession else { return nil }
        let configuration = UIContextMenuConfiguration(identifier: "PointOnlyContextMenu" as NSCopying, previewProvider: { nil }, actionProvider: { suggestedActions in
            let newFolder = UIAction(title: "New Folder", image: UIImage(systemName: "folder.badge.plus")) { [weak self] _ in
                self?.createFolder()
            }
            let info = UIAction(title: "Get Info", image: UIImage(systemName: "info.circle")) { [weak self] _ in
                self?.getInfo()
            }
            return UIMenu(title: "", children: [newFolder, info])
        })
        return configuration
    }
}